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Unhandled error when trying to open new flow

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Posted on by JeffBoring

I have installed Power Automate for Desktop. When I try to open and create a test flow I start getting Unhandled errors. I am forced to use Task Manager to kill the app in order to get out of the endless loop of errors. I deleted the app and reinstalled to see if that would fix it but it did not.

Here is error message:

Message = Object reference not set to an instance of an object. Error = System.NullReferenceException Full text = System.NullReferenceException: Object reference not set to an instance of an object. at System.Windows.Automation.Peers.AutomationPeer.EnsureChildren() at System.Windows.Automation.Peers.AutomationPeer.UpdateChildrenInternal(Int32 invalidateLimit) at System.Windows.Automation.Peers.ItemsControlAutomationPeer.UpdateChildren() at System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree() at System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree() at System.Windows.Automation.Peers.AutomationPeer.UpdateSubtree() at System.Windows.ContextLayoutManager.fireAutomationEvents() at System.Windows.ContextLayoutManager.UpdateLayout() at System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg) at System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks() at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget) at System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget) at System.Windows.Interop.HwndTarget.OnResize() at System.Windows.Interop.HwndTarget.HandleMessage(WindowMessage msg, IntPtr wparam, IntPtr lparam) at System.Windows.Interop.HwndSource.HwndTargetFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)

Any help would be appreciated. Thanks, Jeff

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Power Automate Desktop

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CU16071609-1 6,255 Moderator on at

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Hi @JeffBoring,

I trust you're currently utilizing the latest version 2.41 of Power Automate Desktop. If so, kindly consider downgrading to version 2.39 to see if it resolves your issues.

If you don't have 2.39 version, please message me privately, and I will provide you with the link to access it.

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rguimaraes 10 on at

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Hi,

I had the same problem, and I managed to solve it after doing the pending Windows updates.
Downgrading the version would not solve the problem in my case, as the flows had already been changed in version 2.42.

For Information, these were the updates made:
Update for Windows Server 2019 (KB5034127)
Update for .NET Framework 3.5, 4.7.2 and 4.8 (KB5034273)
I believe it was the .NET Framework update that resolved the problem.

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CU16071609-1 6,255 Moderator on at

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@rguimaraes
Thanks for sharing your insights it may helpful for many people in future as well.

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JK-30071416-0 on at

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THANK YOU!!! This fixed my problem. After going through dozens of posts and trying to clear cache and reinstall, nothing worked. I downgraded which allowed me to create new flows but I couldn't edit flows created in later versions.

Running the Windows Updates solved the problem. Like you, I had the same .NET updates which likely fixed the problem.

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